Aluminum 2218 · precip hard
Aluminum 2218-T71
Properties of the T71 condition, compared with the other 2218 tempers.
Intermediate overaged temper trading some strength for better dimensional stability at elevated temperature.
What is 2218-T71?
2218-T71 is 2218 in the T71 condition — intermediate overaged temper trading some strength for better dimensional stability at elevated temperature. 2218-T71 has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 345 MPa (50 ksi) — stronger than 70% of aluminum grades. Elongation at break is 11% and the elastic modulus is 74 GPa (10.7 Msi). 2218-T71 has a density of 2.81 g/cm³ (0.102 lb/in³), heavier than 86% of aluminum grades. It melts at 505°C (941 °F). T61 is the default condition FabDigit quotes; T71 is available on request or by drawing note.
Advantages
- High service temperature — 230°C (446 °F), better than 95% of aluminum grades
Limitations
- Needs corrosion protection — 33/100, worse than 90% of aluminum grades
- Difficult to weld — 22/100, worse than 83% of aluminum grades
2218-T71 properties
Typical room-temperature values for 2218-T71 — 10 properties are specific to this condition; the rest are grade-level values shared by every 2218 temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
2218-T71 has a density of 2.81 g/cm³ (0.102 lb/in³), heavier than 86% of aluminum grades. It melts at 505°C (941 °F).
Mechanical11
2218-T71 has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 345 MPa (50 ksi) — stronger than 70% of aluminum grades. Elongation at break is 11% and the elastic modulus is 74 GPa (10.7 Msi).
Thermal6
2218-T71 is rated for continuous service to 230°C (446 °F). It conducts heat at 151 W/m·K (87.2 BTU/hr·ft·°F), better than 63% of aluminum grades. Thermal expansion is 22.4 µm/m·K (12.4 µin/in·°F).
Electrical3
2218-T71 conducts electricity at 39 % IACS, better than 65% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (33/100), worse than 90% of aluminum grades.
Sustainability4
Producing a kilogram of 2218-T71 takes about 205 MJ of energy and emits 12.5 kg of CO₂ — more than 75% of aluminum grades. Typical recycled content is 20%.
Manufacturability6
2218-T71's machinability is very good (70/100, better than 72% of aluminum grades); weldability poor (22/100); formability poor (28/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 2218 tempers and conditions
2218 is also supplied in 3 other conditions. The full side-by-side table is on the 2218 overview.
- T61DefaultStandard high-strength temper for 2218 pistons and engine forgings; mild quench limits distortion and residual stress.305 MPa yield · 115 HB
- T6Generic peak-aged designation; for 2218 forgings it is supplied in practice as the T61 variant.305 MPa yield · 115 HB
- T71Intermediate overaged temper trading some strength for better dimensional stability at elevated temperature.275 MPa yield · 105 HB
- T72Choose for pistons and hot-running parts where growth-free dimensional stability above 200 °C matters more than peak strength.255 MPa yield · 95 HB
Working with 2218-T71
Is 2218 easy to machine?
Machines well in T61/T72 with sharp carbide tools and flood coolant, but Ni/Fe intermetallics are abrasive — expect faster edge wear than 6061; chips break cleanly at moderate feeds.
Can 2218 be welded?
Not recommended for fusion welding (hot-cracking of the Al-Cu-Ni system); join by mechanical fasteners or resistance/friction-stir methods with qualified procedures.
Can 2218 be formed, bent or molded?
A forging alloy — hot forge/upset around 400–455 °C; cold forming in aged tempers is very limited, form only in F or freshly solution-treated condition.
What surface finishes work on 2218?
Hard anodize or chromate/organic coating for corrosion and wear protection; decorative anodizing yields a dull grey-brown tone, and polishing reveals coarse intermetallic streaks.
2218 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Si | ≤ 0.9 | 0.4 |
| Feforms Al-Fe-Ni intermetallics that give hot strength | ≤ 1 | 0.6 |
| Cu | 3.5 – 4.5 | 4 |
| Mn | ≤ 0.2 | 0.05 |
| Mg | 1.2 – 1.8 | 1.5 |
| Cr | ≤ 0.1 | — |
| Nikey elevated-temperature addition | 1.7 – 2.3 | 2 |
| Zn | ≤ 0.25 | — |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.15 | — |
| Al | balance | — |
2218-T71 — frequently asked
What is 2218-T71 used for?
2218-T71 is typically used for forged engine pistons, cylinder heads, turbocharger impellers, jet-engine rings, high-temperature forged brackets and hot-end machined engine hardware. In short: engine pistons; heat-resistant.
What is the yield strength of 2218-T71?
2218-T71 has a typical yield strength of 275 MPa (39.9 ksi) and a tensile strength of 345 MPa (50 ksi) — stronger than 70% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is 2218-T71 easy to machine?
Yes — machinability is rated very good (70/100, better than 72% of aluminum grades). Machines well in T61/T72 with sharp carbide tools and flood coolant, but Ni/Fe intermetallics are abrasive — expect faster edge wear than 6061; chips break cleanly at moderate feeds.
Can 2218-T71 be welded?
Not readily — weldability is rated poor (22/100). Not recommended for fusion welding (hot-cracking of the Al-Cu-Ni system); join by mechanical fasteners or resistance/friction-stir methods with qualified procedures.
What surface finishes work on 2218-T71?
Hard anodize or chromate/organic coating for corrosion and wear protection; decorative anodizing yields a dull grey-brown tone, and polishing reveals coarse intermetallic streaks.
Can 2218-T71 be formed, bent or molded?
A forging alloy — hot forge/upset around 400–455 °C; cold forming in aged tempers is very limited, form only in F or freshly solution-treated condition.
What is the maximum service temperature of 2218-T71?
2218-T71 is rated for continuous use to about 230°C (446 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 2218-T61 and 2218-T72?
T61 is the default condition — standard high-strength temper for 2218 pistons and engine forgings; mild quench limits distortion and residual stress. T72: choose for pistons and hot-running parts where growth-free dimensional stability above 200 °C matters more than peak strength. Yield strength is 305 MPa in T61 versus 255 MPa in T72.
Can FabDigit make parts in 2218-T71?
Yes — 2218-T71 is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — The Aluminum Association (2018)
- ASM Handbook Vol. 2: Properties and Selection — Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- Aluminum: Properties and Physical Metallurgy — ASM International (1984)
- EN 573-3 Aluminium and aluminium alloys — Chemical composition — CEN (2019)
- Aluminium alloy property tables (2xxx elevated-temperature forging alloys) — MatWeb / ASM Alloy Center (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.